Replacing Worn Bearings on a Planer

Changing out ball bearings may be a job for a specialist. Even so, here's a detailed description of how it's done. November 28, 2006

I have a Buss 4L planer that I purchased rebuilt in 1999. When I received the machine, the right side bearing of the cutter head had a light tick you could hear if you spun the cylinder by hand. The noise is now growing to a clunk. Would you try to change these yourself?

Forum Responses
(Solid Wood Machining Forum)
From contributor F:
Unless you've had experience doing that sort of thing, I would let someone else do it. It takes the right tools to get the bearings off and on. And if it's not done right, the bearings will fail and have to be replaced again.

From contributor T:
Not familiar with that model/make of machine, as I am in Europe. If it's a small, standalone, simple surface planer, here's what you do if you're going to do it on site. I'm assuming you can remove the cast iron tables covers, etc. Run the drive v-belts of the pulley. Get the cutter block or cylinder out of the machine. Get the bearing numbers off either the shields or the races and check with a supplier. Make sure they are available before you try to remove old ones. They are not going to be used again, so the best way is to hit them on the inner race, working on opposite sides of it progressively till they are off the journal. If you can't hit directly on the inner race, simply hit the outer race till they move or the outer race breaks and balls go flying everywhere. If this happens, get a cutting disc or high speed hand grinder and cut the inner races off without cutting into the shaft journal. Give the journals a light rub of fine emery cloth to remove any fretting or corrosion marks. Smear some anti-seize compound or regular multi-purpose grease on the journals. This will reduce friction for fitting of new ones and also make it easier for the next owner of the machine to change them in 10 years time (very thoughtful).

Unpack your new bearings and place squarely on the journals. Now this part is important. Hit the inner races lightly till they begin to engage the journal, again working progressively till they are fully home against their respective shoulders, making sure they are always square while doing so. If you hit the outer races sufficiently, they will suffer from brinnelling (not sure if spelling is right), which basically means the ball will leave indentations on the races. We don't want that. If the bearings are pre-packed with grease, fit as they are. If they are open type with protection from shields in the bearing housing, just put a finger full on, as too much can cause them to overheat if excess can't escape. If all goes well, replace your pulley and refit everything in the opposite order of removal.

All this should be done with the electric supply isolated and the blades removed from the head, of course. If you're not stuck for time and money, you can send it out to a machine shop, which in a lot of cases will do the same, while some will have a hydraulic press, but will be no cleaner than your own place. We are not talking about the wheel bearings on a formula one car (champ car to you), so don't believe all the "gotta be a specialist" lines you'll hear. The bearings have been operating in damp/dry dusty conditions for years before they gave up, so even a little corrosive sweat from your hands isn't going to ruin them within minutes of starting the machine up.

From the original questioner:

Thanks for the effort in the description. This is not a belt driven cutter, but a direct motor drive. The cutting cylinder is 5" diameter and 26" long, with the motor beyond that. Pricing the two bearings reveals a cost of $490 each. I called some motor shops that said they do this work, so I will get unstuck on cash as you say, and let them have at it. I worry about it being done right, because this is a good machine, but is not made anymore. I hope you are right about it not taking a specialist.

From contributor R:
I'd call for a price on bearings. I had to replace some bearings on our moulder and they saved me hundreds of dollars with comparable bearings. Definitely have someone with experience do the job.

From contributor T:
I understand your setup. It sounds like a bit of a beast. I have done a few of those in my time, big, long shaft, lots of weight and difficult to get into a hydraulic press because of the length. Does the motor run 2800rpm like over here, or does it use a frequency changer (inverter) setup to get extra revs from the motor? I hope the bearings haven't fretted the shaft journals by spinning on them if they seized. If they have, you could build them with a manual stick welder. Then have them skimmed back to diameter, but not too much welding at a time, as overheating could build up on middle journal and affect the shaft straightness. When it comes to the motor end casings or flanges, they are probably cast iron, so don't be tempted to hit them on the lugs that the bolts pass through, as they can snap off. Tap around the periphery with a mallet till they are free. One of the casings might have the bearing retained by a circlip to limit end float, so don't force by impact or pressing.

From the price of the bearings, they sound like big ones, so I understand your concern. Shop around like the other response said - you might be surprised. There are other good makes like Nadella and Cooper about. If you go to a motor shop, have them check the windings while it's apart. Just for the peace of mind. And go for a shop that has experience rather than someone that calls themselves specialists. Anyone can get a job for a specialist - go on a training module for three days with a manufacturer and get a certificate and call themselves a specialist thereafter.